Calcium uptake and calcium transporter expression by trophoblast cells from human term placenta

Laboratoire de Physiologie materno-foetale, Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succursale "Centre-Ville", Montreal, Quebec, Canada H3C 3P8.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 09/2002; 1564(2):325-32. DOI: 10.1016/S0005-2736(02)00466-2
Source: PubMed


Placental transfer of maternal calcium (Ca(2+)) is a crucial step for fetal development although the biochemical mechanisms responsible for this process are largely unknown. This process is carried out in vivo by the placental syncytiotrophoblast layer. The aim of this study was to define the membrane gates responsible for the syncytiotrophoblast Ca(2+) entry, the first step in transplacental transfer. We have investigated the basal Ca(2+) uptake by primary culture of human term placenta syncytiotrophoblast. Kinetic studies revealed an active extracellular Ca(2+) uptake by cultured human syncytiotrophoblast. We demonstrated by Northern blot the presence of transcript for calcium transporter type 1 (CaT1) in cultured human syncytiotrophoblast and CaT1 expression was further confirmed by reverse transcription polymerase chain reaction (RT-PCR). In addition, the expression of calcium transporter type 2 (CaT2) was revealed by RT-PCR in cultured human syncytiotrophoblast. It has been reported that the activity of this family of Ca(2+) channels is voltage-independent, and is not sensitive to L-type Ca(2+) channels agonist and antagonist. Interestingly, modulation of membrane potential by extracellular high potassium concentration and valinomycin had no effect on the basal Ca(2+) uptake of human syncytiotrophoblast. Moreover, the addition of L-type Ca(2+) channel modulators (Bay K 8644 and nitrendipine) to the incubation medium had also no effect on the basal Ca(2+) uptake, suggesting that the process is mainly voltage-independent and does not involved L-type Ca(2+) channels. On the other hand, we observed that two known blockers of CaT-mediated Ca(2+) transport, namely extracellular magnesium (Mg(2+)) and ruthenium red, dose-dependently inhibited Ca(2+) uptake by cultured human syncytiotrophoblast. Therefore, our results suggest that basal Ca(2+) uptake of human syncytiotrophoblast may be assured by CaT1 and CaT2.

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Available from: Robert Moreau, Mar 13, 2014
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    • "CaBP-9k is known to facilitate intracellular Ca2+ transport from the apical to the basolateral cell membrane and functions additionally as an intracellular buffer of Ca2+ in many tissues, such as intestine, bone, uterus and placenta [10]. The expression, and to a certain extent, the regulation of CaBP-9k and TRPV6 in female reproductive tissues is well documented in several mammalian species, such as rat, mouse, pig and human [5,11-14]. Unlike in Ca2+-absorbing organs like the duodenum, where the expression of these proteins is regulated mainly via vitamin-D, their expression in the female reproductive system seems to be regulated via the steroid hormones progesterone and estrogens [2,11,12]. Interestingly, there are distinct variations in the expression and regulation of both proteins among different mammals, which explains their species-specific, dynamic expression patterns during the estrous cycle and pregnancy [1,2,11]. "
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    ABSTRACT: BACKGROUND: Transient receptor potential channel type 6 (TRPV6) and Calbindin-D9k (CaBP-9k) are involved in the active calcium (Ca2+) transport mechanism in many tissues including placenta and uterus, suggesting a role in the establishment and maintenance of pregnancy. Moreover, TRPV6 and CaBP-9k seem to support the materno-fetal Ca2+ transport that is crucial for fetal Ca2+ homeostasis, bone growth and development. However, it is unknown if these proteins are also involved in the aetiology of pathologies associated with parturition in cows, such as retained fetal membranes (RFM). The aim of the current study was to create an expression profile of uterine and placentomal TRPV6 and CaBP-9k mRNAs and proteins during pregnancy and postpartum in cows with and without fetal membrane release. METHODS: Uteri and placentomes of 27 cows in different stages of pregnancy and placentomes of cows with and without RFM were collected. Protein and mRNA expression of TRPV6 and CaBP-9k was investigated by real-time PCR, immunohistochemistry and Western blot. RESULTS: In the uterine endometrium, highest TRPV6 and CaBP-9k expression was found in the last trimester of pregnancy, with a particular increase of protein in the glandular epithelium. In the placentomes, a gradual increase in TRPV6 mRNA was detectable towards parturition, while protein expression did not change significantly. Placentomal CaBP-9k expression did not change significantly throughout pregnancy but immunohistochemistry revealed an increase in staining intensity in the maternal crypt epithelium. Immunohistochemical, stronger placental CaBP-9k signals were seen in animals with RFM compared to animals with an undisturbed fetal membrane release, while protein levels, measured by Western blot analyses did not change significantly. CONCLUSIONS: The results of the present study demonstrate a dynamic expression of TRPV6 and CaBP-9k during pregnancy in the bovine uterine endometrium and placentomes, suggesting a functional role for these proteins in Ca2+ metabolism during pregnancy. The temporal and spatial expression patterns indicate that TRPV6 and CaBP-9k may be involved in materno-fetal Ca2+ transport, mainly through an interplacentomal transport, and that both proteins may participate in physiological processes that are crucial for fetal and placental development. However, neither TRPV6 nor CaBP-9k seem to be causative in the retention of fetal membranes.
    Full-text · Article · Aug 2012 · Reproductive Biology and Endocrinology
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    • "The main functions of syncytiotrophoblasts are absorption, exchanges and specific hormonal secretion (Malassine, 2001). Syncytiotrophoblasts are the primary site of fetal Ca 2+ homeostasis regulation which includes mechanisms characterized by Ca 2+ entry, cytosolic diffusion and extrusion (Moreau et al., 2002; Belkacemi et al., 2005; Lafond and Simoneau, 2006). "
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    ABSTRACT: Lantana macrophylla Schauer (Verbenaceae) a medicinal plant used to treat menstrual and respiratory disorders was investigated. The ethanolic extract from leaves was subjected to phytochemical and biological analysis. BeWo and JEG-3 cells were used to evaluate human chorionic gonadotropin hormone (hCG) production, syncytial formation, Ca2+ uptake and Ca2+ handling protein expression. The cAMP production and the mitogen-activated protein kinases (MAPKs) phosphorylation were also investigated. Phytochemical analysis yield three triterpenes: oleanolic, ursolic and latonolic acid. Viability assay showed no significant cytotoxic effect. A significant decrease in hCG production but not a disturbance on BeWo cell fusion were observed. The cAMP pathway was not affected by L. macrophylla extract alone; although the cAMP production inducted by forskolin was diminished. Both ERK1/2 and p38 MAPKs pathways were activated. Increased intracellular Ca2+ concentration ([Ca2+]i) was observed after 24 h treatment in a time and dose dependent manner; however only L. macrophylla at 10 μg/mL induced increased [Ca2+]i after 10 min treatment. CaBP28K and PMCA1/4 were modulated at protein and mRNA levels, respectively. This study showed for the first time the effect of triterpenoids from L. macrophylla leaves on trophoblasts-like cells and indicates a potential toxic effect of this plant in the placental development and fetal growth.
    Full-text · Article · Dec 2011 · Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association
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    • "In the kidney, TRPV6 is expressed in the convoluted tubules, connecting tubules, and cortical and medullary collecting ducts of the nephron, where it helps resorb Ca 2ϩ (Nijenhuis et al., 2003). In the placental trophoblast, TRPV6 contributes to the transfer of Ca 2ϩ from mother to fetus (Moreau et al., 2002; Suzuki et al., 2008) and may contribute to the reduced litter size of TRPV6(Ϫ/Ϫ) mice (Bianco et al., 2007). "
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    ABSTRACT: Transient receptor potential (TRP) channels are a large family of ion channel proteins, surpassed in number in mammals only by voltage-gated potassium channels. TRP channels are activated and regulated through strikingly diverse mechanisms, making them suitable candidates for cellular sensors. They respond to environmental stimuli such as temperature, pH, osmolarity, pheromones, taste, and plant compounds, and intracellular stimuli such as Ca(2+) and phosphatidylinositol signal transduction pathways. However, it is still largely unknown how TRP channels are activated in vivo. Despite the uncertainties, emerging evidence using TRP channel knockout mice indicates that these channels have broad function in physiology. Here we review the recent progress on the physiology, pharmacology and pathophysiological function of mammalian TRP channels.
    Full-text · Article · Sep 2010 · Pharmacological reviews
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